Speed regulator



March 14, 1950 R. LEE 2,500,190

SPEED REGULATOR Filed Dec. 6 1943 2 Sheets-Sheet 1 FIG. F1114III/11111111111.

IN VENTOR ROYAL LEE 5r il ue ATTORNEY March 14, 1950 R. LEE 2,500,190

SPEED REGULATOR I Filed Dec. s, 1945 2 Sheets-Sheet 2 .FIGJZ PatentedMar. 14, 1950 SPEED REGULATOR Royal Lee, Milwaukee, Wis., assignor toLee Engineering Research Corporation, Milwaukee, Wis, a corporation ofWisconsin Application December 6, 1943, Serial No. 513,086

1 Claim. 1

The present invention relates to speed regulators.

An object of the invention is to provide an improved speed regulatorwhich is capable of controlling the speed of an electric motor withinclose limits.

Another object is to provide a speed regulator including an improvedswitch device which is so arranged as to permit a high rate of contactvibration.

A further object is'to provide a speed regulator which is relativelyfree from gravitational effects and which is so arranged as to simplifywiring connections.

A still further object is to provide a speed regu lating switch devicewhich is of simple and durable construction and which is capable ofinexpensive manufacture.

The invention further consists in the several features hereinafterdescribed and claimed.

In the accompanying drawings, illustrating certain embodiments of theinvention,

Fig. 1 is a side elevation of an electric motor provided with a speedregulator of the invention, parts being broken away and parts beingshown in section;

Fig. 2 is an end view of the motor with parts removed and showing arotatable switch actuator on the motor shaft;

Fig. 3 is an elevation of an end casing of the motor and showing a speedregulating switch device carried by the casing;

Fig. 4 is a sectional view taken generally on the line 44 of Fig. 3;

Fig. 5 is a detail view of the switch device, parts being broken awayand parts being shown in section;

Fig. 6 is a detail elevation of an insulating support of the switchdevice;

Fig. 7 is a diagrammatic view showing one form of circuit for the motorspeed regulator;

Fig. 8 is a view generally similar to Fig. 1, but showing a modifiedform of switch device in which the contacts are arranged to close onincrease of motor speed;

Fig. 9 is an elevation of another modified form of switch deviceincluding a plurality of switch units;

Fig. 10 is a side elevation of the switch device of Fig. 9, parts beingbroken away and parts being shown in section;

Fig. 11 is a top view of the switch device of Fig. 9;

Fig. 12 is a sectional elevation similar to Fig.

10, but showing a further modified form of switch device;

Fig. 13 is a diagrammatic view showing a form of motor controllingcircuit including the switch devices of either Fig. 9 or Fig. 12;

Fig. 14 is a diagrammatic view of a modified form of motor controllingcircuit in which the speed is controlled by an electrical characteristicof the motor;

Fig. 15 is a detail view of a resilient spider for the switch actuatingmeans of Fig. 14;

Fig. 16 is a side elevation, partly in section, showing a modified formof switch mounting, and

Fig. 17 is a view similar to Fig. 16, but showing another form of switchmounting.

In that form of th invention shown in Figs. 1 to 6, I5 designates avariable-speed electric m0- tor having a rotor shaft It. By way ofexample, the motor may be of the series or universal type, as indicatedin Fig. '7, although the invention is applicable to other types ofmotors.

A hub member I! is rigidly secured to an end of the motor shaft and isprovided with flat radial arms 18 extending in opposite directions. Fiatweight-forming link bars l9 are pivotally secured to the respective hubarms I8, as by shoulder rivets 20, and project outwardly therefrom, theaxes of the rivets being equidistant from, and parallel to, the shaftaxis. A bent wire biasing spring M is secured at opposite ends to thepivoted bars 1'9, as by soldering or welding, and urges these bars tothe angular position seen in Fig. 2, each bar being angularly displacedin the direction of rotation from a radial position. The link bars arethus resiliently coupled to the motor shaft. A bowed leaf spring 22 ispivotally secured at its outer ends to the outer ends of the link barsl9, as by means of shoulder rivets 23 which are equidistant from, andparallel to, the shaft axis. The center line of the bowed leaf springlies in the plane of the shaft axis, and the pivot rivets 23 also lie inthis plane. The middle portion of the bowed leaf spring is spacedaxially from the end of the motor shaft and has secured thereto a button24 of fibre or other insulating material.

coaxial with the shaft. The button 24 is adapted to engage a movableelement of a switch or circuit-closer device hereinafter described.

The spring-biased link bars I9 form centrifugally-influenced weightmembers and also form inertia members responsive to changes in motorspeed, these bars having a degree of freedom of movement about theiraxes of rotation and having a component of tangential movement withrespect to the motor shaft. The link bars thus provide both radial andtangential in-, ertia action. Under the influence of centrifugal force,the link bars are urged outwardly toward radial positions against theaction of the biasing spring, thus tending to straighten the bowed leafspring 22 and axially displacing the middle portion of the spring towardthe adjacent end of the rotating motor shaft. Upon a momentary increasein motor speed the rotative speed of. the outer ends of the link bars,by reason of the inertia of these bars, will tend to remain at theformer value and thus lag behind the motor speed. As a result, the linkbars will swing outwardly against the action of the biasing spring andeffect an axial retraction of the bowed leaf spring. In a similar mannera momentary decrease in motor speed will effect an axial advance of thebowed leaf spring.

An apertured cup-shaped end casing 25 is detachably secured to thehousing or frame of the motor i5, as by screws 26, the end casing havinga central screw-threaded bushing 21. A switch or circuit-closer assemblyis detachably mounted in the end casing and comprises a pair ofcooperating contacts 23 and 29 secured to the upper ends of respectiveradiator plates 30 and II, the lower ends of these plates being rivetedor otherwise secured to respective leaf springs 32 and 33, thus formingspring arms for the contacts. At their lower ends the leaf springs 32and 33 are secured by respective rivets 34 and 35 to respectiveinsulating plates 36 and 31, these plates being secured together as byrivets 33. Fig. 3, and there being an interposed insulating sheet 39 toprevent short-circuiting between the rivets 34 and 35. The insulatingplate 33 is iulcrumed at its lower end on the lower portion of the endcasing and for this purpose is provided with guide lugs 40 disposed inopenings 4i in the casing. Upwardly projecting flngers 42 are formed atopposite sides of the insulating plate 36 and are spaced laterally fromthe leaf spring 32 and contact-carrying radiator plate 33. A metalbridge member 43 is secured. as by rivets 44, to the upper ends of thefingers 42 of the insulating plate 39 and is provided with an insulatingliner 4!. The middle portion of the bridge member is offset so as toallow for angular deflection of the contact-carrying arm 33, 32, whichis free to vibrate. spring 43 connects the bridge member 43 and the endwall of the casing member 25 to urge the circuit-closer assembly awayfrom the rotary actuator and hold the lugged insulating plate 36 down infirm fulcrumed engagement with the casing member. threaded in thebushing 21 and bears at its inner end on the middle portion of thebridge member 43 to adjust the angular position of the circuitcioserassembly. The radiator plates extend across the projected axis of themotor shaft approximately at right angles to this axis, and theinsulating button 24 is adapted to bear on the radiator plate 3i to urgethe contact 29 against the contact 28. The leaf spring 33 is biased tourge the contact 29 away from the contact 28, as seen in Fig. 5, so thatthe retraction of the actuator button will cause the contacts toseparate. The adjusting screw 41 may be retained in adjusted position bya lock nut 48. When the adjusting screw 41 is turned outwardly asumcient distance the spring 46 swings the circuit-closer assembly awayfrom the actuator button 24 and the leaf spring 33 then holds thecontact 29 out of engagement with the contact A coiled tension Anadjusting screw 41 isv 23. Current is conducted to the circuit-closercontacts by flexible conductors 43 and 33 connected to the lower ends ofthe respective leaf springs 32 and 33. these conductors avoidinginterference with the angular adjustment of the circuit-closer assembly.

The centrifugally actuated circuit-closer or interrupter can be utilizedin various circuits and by way of example is shown in Fig. 7 to beconnected in series with the motor II which is supplied with currentfrom mains II. The circuit-closer may be shunted by a suitable sparksuppressor, such as a condenser 52. and if desired may be shunted by aresistor 53 which passes part of the motor current. The resistor willalso form a path for the discharge current of the condenser.

When the motor is to be operated, the adjusting screw 41 is turnedinwardly to effect engagement of the contacts 23 and 29. The motor isstarted in operation by connecting it to the supply mains to admitcurrent to the motor, the motor current flowing through the then closedcontacts. The motor accelerates to a critical speed at which thespring-biased contact 29 separates from the contact 23 incident to theaxial retraction of the button 24 carried on the centrifugal actuator,thus reducing the motor current and causing the motor speed to dropslightly. The contacts then re-engage under the pressure of the rotarybutton 24 which advances axially upon reduction of motor speed, causingthe motor speed to again increase slightly, and the cycle of operationis repeated. By the action of the centrifugal actuator the springmountedcontact 29 is caused to vibrate at a high frequency, for example 50 to500 cycles per second, and the motor speed remains substantiallyconstant. The pivoted rotating inertia members i9 are quickly responsiveto slight changes in motor speed, no as to permit rapid axial vibrationof the actuator button 24 which controls the vibratory spring-mountedcontact 29.

When the higher speed of operation is desired the adjusting screw 41 isturned inwardly, and, conversely, when a lower speed is desired theadjusting screw is turned outwardly. By turn ing the screw outwardly asuflicient distance the contacts 28 and 29 will remain open, whereuponthe motor current will be limited by the resistor 53.

It is desirable to permit a slight sparking between the contacts 28 and29, as the explosive efl'ect of the sparking has a tendency to separatethe contacts and appears to be the force which maintains the vibrationof the contact carrying spring arm 32. This spring arm freely vibratesat or near its natural frequency, and its travel in one direction islimited by the engagement of the contacts. The rate of vibration of thecontact 29 is usually much lower than that of the contact 28. Undercertain motor load conditions the contact 29 may move quite slowly, ormay even remain stationar for a short time, but the contact 29 willnevertheless continue to vibrate.

In a centrifugal motor speed regulator of the vibrating contact type,the closeness of speed regulation depends to a considerable extent on ithe rate of contact vibration. The speed regulating apparatus of thepresent invention perments a high rate of contact vibration to beobtained while also providing the advantages of a stationary ornon-rotative contact mounting,

such type of mounting obviating the use of current-collector rings andbrushes for conducting current to the contacts.

In the modified form of the invention shown in Fig. 8, the contacts 23'and 29' are arranged to close when the motor speed increases, permittingthe device to be used in circuits requiring this contact relation. Thecontacts 28 and 29' are carried on the upper ends of the respectivespring-mounted radiator plates and 3I', the upper end of the formerbeing hooked to extend over the upper end of the latter and both springarms 32 and 33 being free to vibrate. The construction is otherwisesimilar to that of the device of Fig. 1.

The modified form of switch device or circuitcloser assembly shown inFigs. 9 to 11 is arranged to provide a plurality of current-interruptingcontact sets and is adapted for use in motor circuits such as are shownin Figs. 13 and 14, hereinafter described. A U-shaped insulating plate86, similar to the plate 36 of Figs. 1 and 3, has its lower end securedto the upper portion of an upright leaf spring 90 forming a springhinge, the lower portion of the leaf spring being clamped to a supportI5, which if desired may form a part of the motor housing. Theinsulating plate 86 carries insulating members 81 and 89 similarto themembers 31 and 39 of Fig. 3. The plate 86 has upwardly projecting sidefingers 92 to the upper ends of which are secured a bridge member 93with an insulating liner 95. The switch device comprises two sets ofcooperating contacts 18 and 19 secured to the upper ends of respectiveradiator plates 88 and 8|, the lower ends of these plates being rivetedto or otherwise secured to the respective leaf springs 82 and 83. Attheir lower ends the leaf springs 82 and 83 are secured, as by riveting,to the insulating plates 83 and 81. The leaf springs 82 are arrangedside by side, and the leaf springs 83 are similarly arranged side byside, and are preferably arranged .for independent vibration. Theradiator plates H are rigidly connected by a cross bar 9| on which bearsthe button 24 of the speed-responsive switch actuator. The cross bar isof insulating material in cases where it is desired to insulate the twocontacts "I9.

The speed-responsive switch of Figs. 9 to 11 can be utilized in variouscircuits one of which is shown in Fig. 13. In this circuit the switch isconnected in series with a series motor I5 supplied with current frommains 5I, the two pairs of contacts I8 and I9 being arranged to providetwo breaks in series so as to divide the break voltage between them.Each pair of contacts may be shunted by a suitable spark suppressor,such as a condenser 52 andresistor 53. One set of correspondingcontacts, say the contacts I9, are electrically connected, while theother two corresponding contacts form the terminals of the switch.

The operation of the system is similar to that of Fig. 7, theresiliently mounted contacts 19 vibrating with the speed-responsiveactuator 24, and the resiliently mounted contacts I8 vibrating freely ata high frequency. The vibration of the contacts I8 appears to bemaintained by the explosive effect of the sparking between the opposedcontacts.

The modified switch device of Fig. 12 is similar to that of Figs. 9 to11, except that the radiator plates 80 are rigidly connected by a crossbar 9|, similar to the cross bar 9I, so that the contacts 78 willvibrate in unison. The operation of the 6 device of Fig. 12 is similarto that of Figs. 9 to 11.

In the motor controlling system of Fig. 14 the speed regulating switchis actuated by means responsive to an electrical characteristic whichvaries with the motor speed. In the present instance use is made of thefact that the motor armature voltage increases with the speed. In thissystem III'I designates a variable speed electric motor, here indicatedto be a series motor of the universal type having a rotor or armatureIII and field coils N2, the armature being connected between the fieldcoils and the latter being connected to current mains H3 furnishingeither direct or alternating current.

The speed regulating switch is preferably of the type shown in Fig. 9,and the two switch units comprising the contacts I8 and 19 thereof areconnected in series between one armature brush and one of the fieldcoils by respective conductors H4 and H5, so as to complete the motorcircuit when the contacts are engaged. Preferably, two series-connectedresistors I I6 and I H are shunted across the terminals of the switch topass part of the motor current when the switch units are open, thejunction between the resistors being connected to the switch contacts I9by a conductor H8. The resistors are shunted by respective protectivecondensers I I9 and I20 and by respective normally open switches I2I andI22.

The position of the contacts I9 of the switch de vice is controlled by areciprocatory actuator 24' carried by a plunger rod I23 secured to theshiftable coil I24 of an electromagnetic device I25 of the moving coiltype commonly used for loud speakers. The plunger rod I23 is supportedfor straight line motion by suitable resilient spiders I26, one of whichis shown in detail in Fig. 15. The field structure I2I of theelectromagnetic device is here shown to be of the permanent magnet type.The moving coil I24 is supplied with current through a bridge typerectifier I28, as of the copper oxide type, one of the input terminalsof the rectifier being connected by a conductor I29 to one of thearmature brushes, and the other input terminal being indirectlyconnected to the other armature brush by way of a conductor I30. Anadjustable impedance I3I is preferably connected in the conductor I29and is adapted to form a speed control. In some instances a condenserI32 may be connected across themoving coil I24. The moving coil systemis of relatively light weight and is quickly responsive to voltagechanges.

In the operation of the system of Fig. 14, electric current, eitheralternating or direct, flows through the motor windings from the mains II3 by way of the contact members I8 and 19 of the two series-connectedswitch units, causing the motor armature to rotate and increase inspeed. As the motor speed increases the voltage across the armature alsoincreases and is impressed on the input terminals of the rectifier,causing direct current to fiow through the moving coil I24. The coil andthe attached actuator are thereby displaced in a direction to separatethe contacts 18 and 19 of the two switch units, the break voltage beingdivided between the switch units. The motor current thereupon drops to asubnormal value determined by the resistors I I6 and 1, thereby limitingthe motor speed. The separation of the contacts also causes the currentflowing through the moving coil I24 to drop through a subnormal valuedetermined by the resistors H6 and Ill, whereupon the actuator plungermoves outwardly and. recloses the switch contacts I8 and 19. The

motor current thereupon increases, tending to increase the motor speed,and the cycle 01' operation is repeated. Fine regulation of the motorspeed is effected by the high-frequency vibration of the freelyvibratable contact members 18. The net result is that the motor speed isgoverned within close limits. The motor speed may be adjusted by varyingthe position of the switch assembly, as by means of the screw 41 of Fig.10. The moving coil either executes occasional movements or vibrates, asdesired.

If the resistors I I6 and I I 1 are properly set and the switches I21and I22 are both open, the opening and closing of the switch contacts 10and I will have little or no eflect on the actuator coil I24, the coilthen being closely responsive to armature voltage so as to provide goodspeed regulation. With both switches 12! and I2! closed the motor willoperate without speed regulation. The motor may be connected to directcurrent mains without regard to polarity, as the rectifier will insurethe proper polarity of the current flowing through the moving coil I24.

The modified switch device of Fig. 16 is similar to that of Fig. 1except that it is mounted for translation to adjust the speed setting.The insulating plate 38 has a bridge member 43 which is rigidly carriedon the inner end of a stem 91 slidably but non-rotatably fitting in asupport 25', the stem being urged axially toward the ac-- tuator 24 by acoiled spring 96 and being axially adjusted by a nut 00 threaded on theouter end of the stem.

The modified switch device of Fig. 17 has its bridgememberll' rigidlycarried on the inner end of a screw stem 41' threaded in a support 15,the stem having a knob 99' at its outer end. A coiled spring 96 takes upback lash in the threads, and a lock nut 48' on the stem retains thestem in adjusted position. The screw stem is turned through a limitedangle, preferably less than one revolution, for axially shifting theswitch assembly and thereby adjusting the speed setting.

The switch adjusting means of Figs. 16 and 17 may also be applied to theswitch devices 0! Pin. 9 and 12.

This application constitutes a continuation in part of my applicationSerial No. 424,450, filed December 26, 1941, for Speed regulatingapperatus, which has matured into Patent No. 2,303,- 314, granted July11, 1944.

What I claim as new and desire to secure by Letters Patent is:

In a speed regulator for controlling the speed of an electric motorhaving a rotatable armature, a circuit-closer including relativelymovable interrupter contacts, actuating means responsive to the speed orsaid armature for controlling the position of one of said contacts, saidlast-named means including an electromagnetic device with a moving coilresponsive to armature voltage and further including a rectifier forsupplying unidirectional current to said moving coil, and resilientsupporting means for the other contact ireely vibratable to interruptthe engagement of said contacts during the rotation oi said armature.

ROYAL LEI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 438,656 Thomson Oct. 21. 18001,767,146 Lee June 24, 1030 1,795,240 Ulmer Mar. 3, 1031 1,857,202 LeeMay 10, 1082 2,021,196 Oldham Apr. 15, 1030 2,103,589 Lee et a1. Dec.28, 1037 2,113,234 Lee Apr. 5, 1038 FOREIGN PATENTS Number Country Date37,872 Netherlands Apr. 15, 1030

